#ifndef TURING_VTK_HH
#define TURING_VTK_HH

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include "grid.hh"

class vtk_writer {
    unsigned int cnt;
    const std::string basename;
    const structured_grid & grid;
    const std::vector<double> & data;
public:
    vtk_writer (std::string _basename,
        const structured_grid & _grid,
        const std::vector<double> &_data) :
        cnt(0), basename(_basename), grid(_grid), data(_data)
    {}

    void write(int c=-1)
    {
        if (c == -1)
            c = cnt;

        // create filename
        char fname[256];
        snprintf(fname,255,"%s-%05i.vtk", basename.c_str(), c);

        // create file
        FILE *out=fopen(fname, "w");

        // write header
        fprintf(out,"# vtk DataFile Version 2.0\n");
        fprintf(out,"vtk output\n");
        fprintf(out,"BINARY\n ");
        fprintf(out," \n");
        fprintf(out," \n");
        fprintf(out,"DATASET STRUCTURED_POINTS\n");
        fprintf(out,"DIMENSIONS %d %d %d\n",
            grid.size(0), grid.size(1), grid.size(2));
        fprintf(out,"ORIGIN %f %f %f\n", 0.0, 0.0, 0.0);
        fprintf(out,"SPACING %f %f %f\n",
            grid.meshwidth(), grid.meshwidth(), grid.meshwidth());
        fprintf(out," \n");
        fprintf(out,"POINT_DATA %d\n",
            grid.size());
        fprintf(out,"SCALARS %s float 1\n", basename.c_str());
        fprintf(out,"LOOKUP_TABLE default\n");

        // parallel: Daten an Prozess 0 schicken, damit dieser schreiben kann
        // write data
        unsigned int i[3];
        for (i[2]=0; i[2]<grid.size(2); i[2]++)
            for (i[1]=0; i[1]<grid.size(1); i[1]++)
                for (i[0]=0; i[0]<grid.size(0); i[0]++)
                {
                    unsigned int idx = grid.index(i);
                    // placement new                  
                    float f = data[idx];
                    // byte swap
                    char* c = reinterpret_cast<char*>(&f);
                    static const int n = sizeof(float);
                    for (int i=0; i<n/2; i++)
                    {
                        char t = c[n-1-i];
                        c[n-1-i] = c[i];
                        c[i] = t;
                    }
                    fwrite(&f, 1, n, out);
                }
        fclose(out);
        // update timestep
        cnt = c+1;
    }
};
    
#endif // TURING_VTK_HH